I bough an old house has a fireplace with ITT millivolt valve. The pilot light stays on but cannot get the fireplace burner on. The thermopile voltage is 600 mv. Is it too low? There are four screw terminals on the valve. How do I tell which terminal for thermopile or wall switch? Does the red or white wire of thermopile needed to hooked up certain way? Do I need jumper by the way wall switch terminal and thermopile terminal. Any schematic or suggestion?